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sqlite java——迹忆客-ag捕鱼王app官网
在本章中，您将学习如何在 java 程序中使用 sqlite。
安装
在 java 程序中使用 sqlite 之前，我们需要确保机器上已经有 sqlite jdbc driver 驱动程序和 java。可以查看 java 教程了解如何在计算机上安装 java。现在，我们来看看如何在机器上安装 sqlite jdbc 驱动程序。
- 最新 sqlite-jdbc-(version).jar 版本可以访问 下载。
- 在您的 class 路径中添加下载的 jar 文件 sqlite-jdbc-(version).jar，或者在 -classpath 选项中使用它，这将在后面的实例中进行讲解。
在学习下面部分的知识之前，您必须对 java jdbc 概念有初步了解。如果您还未了解相关知识，那么建议您可以先花半个小时学习下 jdbc 教程相关知识，这将有助于您学习接下来讲解的知识。
连接数据库
下面的 java 程序显示了如何连接到一个现有的数据库。如果数据库不存在，那么它就会被创建，最后将返回一个数据库对象。
import java.sql.*;
public class sqlitejdbc
{
public static void main( string args[] )
{
connection c = null;
try {
class.forname("org.sqlite.jdbc");
c = drivermanager.getconnection("jdbc:sqlite:test.db");
} catch ( exception e ) {
system.err.println( e.getclass().getname() ": " e.getmessage() );
system.exit(0);
}
system.out.println("opened database successfully");
}
}
现在，让我们来编译和运行上面的程序，在当前目录中创建我们的数据库 test.db。您可以根据需要改变路径。我们假设当前路径下可用的 jdbc 驱动程序的版本是 sqlite-jdbc-3.7.2.jar。
$javac sqlitejdbc.java
$java -classpath ".:sqlite-jdbc-3.7.2.jar" sqlitejdbc
open database successfully
如果您想要使用 windows 机器，可以按照下列所示编译和运行您的代码：
$javac sqlitejdbc.java
$java -classpath ".;sqlite-jdbc-3.7.2.jar" sqlitejdbc
opened database successfully
创建表
下面的 java 程序将用于在先前创建的数据库中创建一个表：
import java.sql.*;
public class sqlitejdbc
{
public static void main( string args[] )
{
connection c = null;
statement stmt = null;
try {
class.forname("org.sqlite.jdbc");
c = drivermanager.getconnection("jdbc:sqlite:test.db");
system.out.println("opened database successfully");
stmt = c.createstatement();
string sql = "create table company "
"(id int primary key not null,"
" name text not null, "
" age int not null, "
" address char(50), "
" salary real)";
stmt.executeupdate(sql);
stmt.close();
c.close();
} catch ( exception e ) {
system.err.println( e.getclass().getname() ": " e.getmessage() );
system.exit(0);
}
system.out.println("table created successfully");
}
}
上述程序编译和执行时，它会在 test.db 中创建 company 表，最终文件列表如下所示：
-rw-r--r--. 1 root root 3201128 jan 22 19:04 sqlite-jdbc-3.7.2.jar
-rw-r--r--. 1 root root 1506 may 8 05:43 sqlitejdbc.class
-rw-r--r--. 1 root root 832 may 8 05:42 sqlitejdbc.java
-rw-r--r--. 1 root root 3072 may 8 05:43 test.db
insert 操作
下面的 java 代码显示了如何在上面创建的 company 表中创建记录：
import java.sql.*;
public class sqlitejdbc
{
public static void main( string args[] )
{
connection c = null;
statement stmt = null;
try {
class.forname("org.sqlite.jdbc");
c = drivermanager.getconnection("jdbc:sqlite:test.db");
c.setautocommit(false);
system.out.println("opened database successfully");
stmt = c.createstatement();
string sql = "insert into company (id,name,age,address,salary) "
"values (1, 'paul', 32, 'california', 20000.00 );";
stmt.executeupdate(sql);
sql = "insert into company (id,name,age,address,salary) "
"values (2, 'allen', 25, 'texas', 15000.00 );";
stmt.executeupdate(sql);
sql = "insert into company (id,name,age,address,salary) "
"values (3, 'teddy', 23, 'norway', 20000.00 );";
stmt.executeupdate(sql);
sql = "insert into company (id,name,age,address,salary) "
"values (4, 'mark', 25, 'rich-mond ', 65000.00 );";
stmt.executeupdate(sql);
stmt.close();
c.commit();
c.close();
} catch ( exception e ) {
system.err.println( e.getclass().getname() ": " e.getmessage() );
system.exit(0);
}
system.out.println("records created successfully");
}
}
上述程序编译和执行时，它会在 company 表中创建给定记录，并会显示以下两行：
opened database successfully
records created successfully
select 操作
下面的 java 程序显示了如何从前面创建的 company 表中获取并显示记录：
import java.sql.*;
public class sqlitejdbc
{
public static void main( string args[] )
{
connection c = null;
statement stmt = null;
try {
class.forname("org.sqlite.jdbc");
c = drivermanager.getconnection("jdbc:sqlite:test.db");
c.setautocommit(false);
system.out.println("opened database successfully");
stmt = c.createstatement();
resultset rs = stmt.executequery( "select * from company;" );
while ( rs.next() ) {
int id = rs.getint("id");
string name = rs.getstring("name");
int age = rs.getint("age");
string address = rs.getstring("address");
float salary = rs.getfloat("salary");
system.out.println( "id = " id );
system.out.println( "name = " name );
system.out.println( "age = " age );
system.out.println( "address = " address );
system.out.println( "salary = " salary );
system.out.println();
}
rs.close();
stmt.close();
c.close();
} catch ( exception e ) {
system.err.println( e.getclass().getname() ": " e.getmessage() );
system.exit(0);
}
system.out.println("operation done successfully");
}
}
上述程序编译和执行时，它会产生以下结果：
opened database successfully
id = 1
name = paul
age = 32
address = california
salary = 20000.0
id = 2
name = allen
age = 25
address = texas
salary = 15000.0
id = 3
name = teddy
age = 23
address = norway
salary = 20000.0
id = 4
name = mark
age = 25
address = rich-mond
salary = 65000.0
operation done successfully
update 操作
下面的 java 代码显示了如何使用 update 语句来更新任何记录，然后从 company 表中获取并显示更新的记录：
import java.sql.*;
public class sqlitejdbc
{
public static void main( string args[] )
{
connection c = null;
statement stmt = null;
try {
class.forname("org.sqlite.jdbc");
c = drivermanager.getconnection("jdbc:sqlite:test.db");
c.setautocommit(false);
system.out.println("opened database successfully");
stmt = c.createstatement();
string sql = "update company set salary = 25000.00 where id=1;";
stmt.executeupdate(sql);
c.commit();
resultset rs = stmt.executequery( "select * from company;" );
while ( rs.next() ) {
int id = rs.getint("id");
string name = rs.getstring("name");
int age = rs.getint("age");
string address = rs.getstring("address");
float salary = rs.getfloat("salary");
system.out.println( "id = " id );
system.out.println( "name = " name );
system.out.println( "age = " age );
system.out.println( "address = " address );
system.out.println( "salary = " salary );
system.out.println();
}
rs.close();
stmt.close();
c.close();
} catch ( exception e ) {
system.err.println( e.getclass().getname() ": " e.getmessage() );
system.exit(0);
}
system.out.println("operation done successfully");
}
}
上述程序编译和执行时，它会产生以下结果：
opened database successfully
id = 1
name = paul
age = 32
address = california
salary = 25000.0
id = 2
name = allen
age = 25
address = texas
salary = 15000.0
id = 3
name = teddy
age = 23
address = norway
salary = 20000.0
id = 4
name = mark
age = 25
address = rich-mond
salary = 65000.0
operation done successfully
delete 操作
下面的 java 代码显示了如何使用 delete 语句删除任何记录，然后从 company 表中获取并显示剩余的记录：
import java.sql.*;
public class sqlitejdbc
{
public static void main( string args[] )
{
connection c = null;
statement stmt = null;
try {
class.forname("org.sqlite.jdbc");
c = drivermanager.getconnection("jdbc:sqlite:test.db");
c.setautocommit(false);
system.out.println("opened database successfully");
stmt = c.createstatement();
string sql = "delete from company where id=2;";
stmt.executeupdate(sql);
c.commit();
resultset rs = stmt.executequery( "select * from company;" );
while ( rs.next() ) {
int id = rs.getint("id");
string name = rs.getstring("name");
int age = rs.getint("age");
string address = rs.getstring("address");
float salary = rs.getfloat("salary");
system.out.println( "id = " id );
system.out.println( "name = " name );
system.out.println( "age = " age );
system.out.println( "address = " address );
system.out.println( "salary = " salary );
system.out.println();
}
rs.close();
stmt.close();
c.close();
} catch ( exception e ) {
system.err.println( e.getclass().getname() ": " e.getmessage() );
system.exit(0);
}
system.out.println("operation done successfully");
}
}
上述程序编译和执行时，它会产生以下结果：
opened database successfully
id = 1
name = paul
age = 32
address = california
salary = 25000.0
id = 3
name = teddy
age = 23
address = norway
salary = 20000.0
id = 4
name = mark
age = 25
address = rich-mond
salary = 65000.0
operation done successfully
